Method of improving lubricating oil by adsorption on silica gel



Oct. 30, 1951 l. P. JONES v 2,572,866

METHOD OF' IMPROVING LUBRICATING OILv BY ADSORPTION ON SILICA GEL Filed Dec. 18, 1947 2 SHEETS- SHEET 1 IrzfsZecjv P. Jones 5in/atar Cltborrzeg oct. 30, 1951 P* JONES 2,572,866

METHOD OF IMPROVING LUBRICATING OIL BY ADSORPTION ON SILICA GEL Filed Deo. 18, 1947 2 SHEETS-SHEET 2 50m/ENT v 72 l 50m/:NT L OH- GEL. l Nl-lfi va '71 62N 74N@ U70 6 1 -8 O SEPARATION ENT 54 d 55 a5 S A 7G P 75 '75 laeENEaAw-an HLGH v. l. om 7|? AgQMM-m GEL.

+5oL.\/E.N1 L t F I "Z FzEsL-L l GEL.

O2 HLGH \1.\.o\\ Alom/nca +5o LvENT {50m/ENT 104* OIL. FEU:

io' "\`iQO O l Y 1o@ vaw 7 l 105 REGaNEJLATED A@ T gg E? laslas' PQJorzes Bvb/eater EDSMLMMCltbQrQQ- Agel, activated charcoal, etc.

Patented Oct. 30, 1951 METHOD OF IMPROVING LUBRICATING OIL BY ADSORPTION ON SILICA GEL Insley P. Jones, Oldwick, N. J., assignor to Standard Oil Development Company, a corporation of Delaware Application December 18, 1947, Serial No. 792,519

4 Claims.

The present invention is concerned with an improved process for the segregation of aromatic type compounds from non-aromatic type compounds. The invention is more particularly concerned with the production of high quality lubrieating oils employing adsorbents such as silica gel or equivalents. The invention is specifically concerned with improved methods of regenerating these adsorbents which comprises treating the same at relatively high temperatures, particularly at or near the boiling point of the solvent utilized in the regeneration step.

It is known in the art to segregate various types of hydrocarbon constituents from other types of hydrocarbon constituents using solid adsorbents. For example, it is known that petroleum fractions may be separated into aromatic and non-aromatic fractions by selective adsorption with silica The process utilized may involve complete adsorption of an oil on a relatively large quantity of the solid adsorbent, such as silica gel, which is contained in a treating zone or lter column. The solid adsorbent is then usually treated with a non-polar solvent, such as petroleum hydrocarbons having less than about 8 carbon atoms in the molecule. This treatment is elective in selectively desorbing certain of the adsorbed constituents. For example if a nonpolar solvent such as normal heptane is employed as the treating agent, the normal heptane is removed from the treating zone along with parafnic and naphthenic type constituents which have been desorbed and which may be subsequently segregated from the normal heptane. The adsorbed aromatic components which have not been desorbed by this treatment are subsequently removed from the solid adsorbent and recovered, usually by application of relatively large quantities of a polar solvent, such as methyl alcohol or an acetone-naphtha mixture. In the past, the recovery operations have been conducted at temperatures in the range from about 60 to 90 F. wherein maximum selectivity for the separation is obtained. Complete regeneration of the spent gel is effected by then subjecting it to relatively prolonged steaming at temperatures in the range from about 350 to 500 F. This serves to remove residual organic materials. The gel is then treated at 350-500 F. with a gas such as air or nitrogen, in order to reduce the moisture content and restore the gel to suitable adsorptive ellciency.

While these operations have been satisfactory, the regeneration of the gel is relatively expensive and in many instances prevents its use in commercial operations. I have, however now discovered a process by which solid adsorbents may be readily regenerated and adsorbed paramic and aromatic constituents efficiently recovered.v My invention comprises utilizing only non-polar solvents in the adsorption cycle and in thev regeneration cycle. In accordance with my invention, I regenerate the adsorbent with a non-polar solvent, preferably Vwith a parailinic petroleum hydrocarbon having from about 5 to 8 carbon atoms in the molecule.

The process of my invention may be readily understoodby reference to the drawings illustrating embodiments of the same. Figure 1 illustrates an operation employing a plurality of xed beds. Figure 2 illustrates an adaptation of my invention wherein the solid adsorbent is passed through a treating zone and then through a rey l' generation zone, while Figure 3 illustrates a system wherein the solid adsorbent is maintained in a dispersed phase in the liquid mediums.

In the embodiment shown in Figure 1, the silica gel treating zone is operated in a three step cycle. During the rst step, the absorption step, a feed oil is introduced to the silica Vgel zone so as to attain substantially complete adsorption of the feed oil by the silica gel. During the second step, the desorption step, a paraflinic Wash solvent is introduced tothe silica gel zone, desorbing parafnic and naphthenic constituents of high viscosity index. During the third step, the regeneration step, hot paranic solvent at or near its boiling point is introduced to the silica gel zone, desorbing the remaining adsorbed constituents and regenerating the silica gel.

Referring specically to Figure 1, feed oil, which for the purpose of illustration is assumed to be a light motor lubricant having a gravity in the range from about 28 to 34 degrees A. P. I. and boiling in the range from about 600 to 900 F., is introduced into treating zone Ill by means of feed line I. Prior to introducing the feed oil into treating zone I0 the viscosity of the oil may be adjusted to the desired degree by diluting the feed oil with a non-polar solvent which is introduced into feed line I by means of solvent line 2.

The oil ilows downwardly through treating zone I0 which contains a solid adsorbent which, for the purpose of description, is assumed to be silica gel. The silica gel may be any suitable type of silica gel and may be dispersed in treating zone I0 by any suitable means. For the purpose of illustration, it is assumed that the particle size of the silica gel in treating zone I0 is in the range from about 20 to 200 mesh. The ow of oil through treating zone I0 may be controlled by any known type of distributing and contacting means and baies. Under the particular method of operating, as illustrated by Figure 1, feed is introduced into feed zone I until the silica gel in the zone is substantially completely saturated. At the point at which oil just begins to flow from zone I0 by means of line 3, the feed oil is no longer introduced into zone I0, but is handled as hereinafter described and is passed into treating zone 20. It is to be understood that if it is desired to treat the oil with a relatively large percentage of treat with respect to the silica gel, less oil may be introduced into treating zone ID. The temperature in the initial stage in treating zone I0 is in the general range from about 60 to 90 degrees F.

At this point, a non-polar solvent Which is, for example, a parainic Ytype solvent, the constituents of which have from about to 8 carbon atoms in the molecule and which boils in the general range from about 100 to 250 F. and Which is preferably the same solvent used to dilute the feed oil in the initial cycle, Iis introduced into treating zone I0 by means of line 4. `For the purpose of illustration, it is assumed that the sol- I vent comprises normal heptane. The normal heptane .'flows through treating zone IU and is withdrawn by means' of line'3 and is passed into distillation zone 3B by means of line 5. The normal heptane selectively desorbs the more parafi'lnic and naphthenic types of constituents 'and removes these from treating zone Ill.V These paraflinic type constituents are separated 4from the normal heptane and are recovered as a 'high V. I. Yproduct in distillation zone 30. The normal heptane is removed overhead from treating zone by means of line, condensed in condensing toY treating zone In as a vapor by means of line 9. AIn accordance With my invention, this" treatment, which is effective in regenerating the silica gel in treating zone I 0, is carried out by'contacting the silica, gel vvith'a parailnic type solvent in the liquid phase at a temperature at 'or near the boiling point lof the solvent u'sed.

Th'us, in' accordance with the embodiment of my invention, as illustrated in Figure l, the vaporous n-heptane, at or near the boiling point of n-heptane, is introduced into the top of treat? ingrzone IB by 'means o'f line 9. It is to be understood that the vapor may be introduced 'at a plurality of points to treating zone IU by means of lines II and I2. Treating zone I0 is operated under conditions 'so that substantially 'complete condensation of the vaporous heptane is secured in the ltr'eating "zone This condition may be secured by any cooling or heating means, which lis illustrated in the drawing by means of jacket I3. The hot heptane containing dissolved aromatic constituents is removed fromV the bottom of zone I0 by means ofline 3 and is introduced into distillation zonev 4B by means of 'line I4'. Temperature and pressure conditions are adjusted in zone to recover aromatic type constituents by means of line' I5 and to' remove overhead from zone 4D by means of line I6, vaporous heptane. The' vaporous heptaneispreferably recycled to zone I0 by means of lines II, 6 and 9 as hereinbefore described. v

When the regeneration of the vsilica Vgel has beenaccomplished to the desired degree of `ef 4 ciency,the vaporous heptane removed from zone 4G is passed through condensing zone I by means of line I 8 and may be handled in any manner desirable. In general, it is preferred to employ at least a portion of the same as a diluent for the feed oil. v

Prior to reintroducing the feed oil into treating zone IG, the silica gel is cooled to a temperature`in the range from about to 90 degrees by any suitable means. In general, it is preferred to `recycle the normal heptane through treating zone I 0 and condensing zone 'I in order to remove the heat Treating zone 20 operating in conjunction with treating zone I 0 operates in a similar manner. Zone 2l] is employed When the feed oil is no longer introduced into treating zone I0. For example, when the feed oil is no longer introduced into the treating zone iii at the end of the adsorption cycle for zone I0, it is passed to treating zone 20 to initiate the beginning of the adsorption cycle for treating rone 2li. At the end of the adsorption cycle for treating zone 20, .the feed oil may again be passed to treating zone- I {lor passed to another f zone operating in conjunction with zones IIJ and 2li to start the adsorption cycle for said other zone. -At the end of the adsorption cyclevin zone 2&3, the washing solvent is introduced into the topy ,of zone 2U by means of solvent line '19. The

solvent, for the purpose of illustration, comprises normal heptane.

carbons. During this cycle-.the--normal heptane line 22.- Temperature and pressure conditions are adjusted inzone 50 to remove by meansof line23 parainic type constituents and to remove overhead by means of -line 24 thefnormal heptane. This normal heptane is passed to condensing zone 25 and is preferably recycled to the top of Zone 20.

. When the parafiinicity of the hydrocarbons recovered by means of line 23 has decreased to a predetermined critical figure, the normal heptane removed overhead from zone 5I! is recycled in the vaporous phase to' treating Zone '20 to initiate the start of the -regeneration cycle. As pointed outfheretofore, thel vapors maybe introduced at a plurality of points into zone 2B by means of lines 25, 26 and 2'?. The normalhep'tane c'ontaining dissolved aromatic typeV constituentsis withdrawn from Zone 2@ by means of line' 2| 'and is introduced into distillation Zone 60 'wherein temperature and pressure conditions are adjusted to remove aromatic typ'e constituents by means of line' 2&5 and to remove overhead by means of line 29 the normal heptane.

Referring now to Figure 2, Which illustrates an adaptation of my process'to a 'batch contacting process, silica gel is introduced into mixing zone 'i0 by m'eans of line 'I I. Solvent is introduced into zone 'I0 by means of'line 'I2 while the feedvoil is introduced by means of line 13. Mixing in zone 'i0 is'secured by any suitable means, as 'for example, 'by stirrer le. The mixture vis Withdrawn from zone 79 by means of line T5 'and is passed to filtering or equivalen'ts'eparation means 16.

The para'lnic type constituents along with the solvent are withdrawn by means of line 'I1 from separation means 'Itr and handled in a manner to segregate the solvent and the high viscosity oil. The spent gel is withdrawn fromY rotary filter 16 l by means of line 'I8 and is Ypassed to a regenera- This'solvent flows downward-v ly through treating zone 2) and preferentiallyY desorbs parainic and naphthenic type hydrotion zone 80. Solvent, which for 'example is assumed to be normal heptane at approximately 200 F., is introduced into zone 80 by means of line 8|. Mixing of the silica gel and solvent is secured by any mixing means, which for the purpose of illustration, is assumed to be stirrer 82. The mixture is withdrawn from zone 80 by means of line 83 and is passed to separation means 84 wherein the solvent and the aromatic type constituents are segregated from the regenerated silica gel. The regenerated gel is withdrawn from zone 84 by means of line 85 and is preferably recycled to zone 10. The solvent and the aromatics are withdrawn from filtering means 84 by means of line 86 and are handled in a manner to segregate the aromatic type constituents from the solvent. As discussed heretofore, the solvent employed in zone 80 and in zone I0 comprises a non-polar solvent and is preferably the same solvent.

Referring now to Figure 3, which illustrates an adaptation of my invention wherein the silica gel is maintained in the dispersed phase in the treat-n ing mediums, oil feed is introduced into treating zone by means of feed line |0|. The oil flows upwardly through zone |00 and contacts downflowing silica gel which is introduced intozone |00 by means of line |02. A solvent which comprises a non-polar solvent and Which, for the purpose of illustration, is assumed to be normal heptane, is introduced into zone |00 by means of line |03. A high viscosity index oil and solvent is removed from zone II 00 by means of line |04 and is handled by any suitable means to segregate the oil land solvent. The silica gel containing adsorbed aromatic type constituents is removed from zone |00 by means of line |05 and is introduced into the top of recovery zone H0. Hot solvent, which for the purpose of illustration is assumed to be normal heptane, is introduced into the bottom of zone I|0 by means of line |06. This solvent ows upwardly and countercurrently contacts downflowing silica gel in zone I |0. v The solvent, together with desorbed aromatic type constituents, is removed from zone I I0 by means of line I 01 and is handled to segregate the aromatic type constituents from the solvent. The silica gel, substantially completely free of hydrocarbon constituents, is removed from zone I I0 by means of line |08 and is preferably recycled to zone |00.

The high viscosity index oil and solvent removed from zone |00 by means of line |04 is in-A troduced into recovery zone I 20 wherein the high viscosity index constituents are segregated by means of line |09. The solvent is removed overhead by means of line |06 and is introduced into zone IIO as hereinbefore described. In a similar manner the aromatic type constituents and solvent removed by means of line |01 from zone I I 0 is introduced into distillation zone |30 Wherein the aromatic type constituents are segregated by means of line |3| and the solvent by means Aof line |32 which latter stream is recycled to zone I|0. I

My invention may be further understood by the following examples illustrating various embodiments of the same.

EXAMPLE I A light motor lubricant having an A. P. I. gravity of about 32 degrees was diluted with an equal volume of normal heptane. This mixture was completely adsorbed on 440 Weight percent of fresh silica gel in a filter column at 85 F. The silica gel was then treated with an additional 5 volumes of lnormal heptane. This latter heptane wash removed 62% of the oil charged to the silica gel, which constituents were substantially all nonaromatic materials. The gel containing the aromatic materials was segregated into 5 parts and extracted with various polar and non-polar solvents at their respective boiling points. The resultant gel products were dried at 250 and inspected for their aromatic adsorption index,

which indicates the efficiency of regeneration, the following results as compared to fresh silica gel:

A fifth portion of the gel was washed at 85 F. withv a similar quantity of the 60/40 blend of v acetone-naphtha followed by steaming at 400 F.

and blowing with nitrogen at 400 F. The resulting product showed an aromatic adsorption index of 95, representing 81% efciency.

In the above data it is apparent that normal heptane, a non-polar solvent, may be readily emuployed in accordance with my process for the regeneration of spent silica gel.

EXAMPLE II In a more extended test a light lubricating oil was extracted with silica gel in successive cycles of adsorption and regeneration, the same solvent being employed throughout for initial dilution,

non-aromatic product recovery, and gel regeneration under controlled temperature conditions.

.The following conditions were employed in conventional percolation equipment.

Adsorption conditions Charge stock: Light lubricating oil, 78 V. I.

Gel treat: 440 Wt. of 28-200 mesh silica gel.

Initial oil dilution: vol. of n-heptane .based on oil charge.

Primary wash: 400 vol.' of n-heptane based on oil charge.

Temperature: 85 F.

Regeneration conditions Wash: n-heptane, 2 v./V. based on gel or 1270 vol. based on lube charge.

Regeneration Temperature 85 F. 200 F.

cycle No 1 2 3 4 1 2 4 V. I. of non-aromatic fraction at 60% yield" 115 109 105 104 115 lll 113 112 The advantage of employing an elevated temperature for the regeneration cycle is amply illustrated by the continued high product quality obtained on` successive adsorption cycles.

In a similar run conducted at F. throughout with no dilution of the oil charge, the following data were obtained:

Cycle No V. I. of non-aromatic fraction at 60% yield 110 110 100 106 102 101 These vdata luxdca-.te 'that yalthough:fairly high gel efciency Vwas 'maintained in successive vcycles the non-aromatic product quality "was not as good as obtained when' using' an V85" F. adsorption temperature. 'For maximum advantage, therefore, temperature should be elevated only for the regeneration step.

EXAMPLE 1,11

In av further series of experiments spent gel however, that it is within the scope of my in-..

vention to treat at temperatures somewhat above theboiling point, as forexample, or 50 degrees above the boiling point, so long as vthe system is maintained Vin the liquid phase.

The solvents in general comprise non-polar solvents, as for example, parainic type hydrocarbons or narrow boiling alkylate fractions. In general, .it is preferred that the hydrocarbons containffrom about 3 to l0, preferably from 5 to 8 carbon atoms in the molecule and boil in the general range from about '100 F. to 300 F.

My process is particularly directed toward the regeneration of silica gel employed in the treatment of petroleum oils for the segregation of relatively more paraflinic constituents from relatively less parafnic constituents. Preferred feed oils are those oils boiling in the lubricating oil boiling'range', as for example, in the range from about 600 F. to 900 F. and having A. P. I. grav ity in the range from about 24 to 36 degrees.

In general, the Operation is,conducted at atmospheric pressures although if temperatures slightlyabovethe boiling points of the particular solvent are used, somewhat higher pressures will be necessary in order to maintain the solvent in the liquid phase. For example, as in Example I, normal heptane wasr employed to regenerate silica gel. Pressures of 50 pounds p, s. i., and 85 pounds p. s. i., were employed rather thanrthe atmospheric pressureemployed in Example I; the treating temperatures were then 300 F`. and 350 F., respectively. These temperatures were substantially at the boilingpoint of the normal heptane under the conditions of pressure specied. It was found that the regeneration was as effective at the higher pressuresas at atmospheric pressure, and `furthermore it was unexpectedly discovered that less normal heptane was required to secure equivalent regeneration of the gel. At both hfigh pressure runs it was found that 11/2 volumes of normal heptane per volume of silica gel was as effective as 2 volumes of normal heptane per Volume of silica .gel employed at atmospheric pressure. lIt is, therefore, contemplated that regeneration according to this invention may beconducted at pressures in the range of I to-loyatmospheres at the temperature substantially corresponding to they boiling temperav l l mi ture .of :the tdesorbent atv the particular pressure employed. y

Having -now fully 1described my invention, 'I claim: 1. A silica gel lubricating oil treating process in which lubricating oil diluted with al paraffinic hydrocarbon containing fromI about 3 to 10 carbon atoms and boiling in the range of about to 300 F. is substantially adsorbed on silica gel by contact therewith, subsequent to said contacting washing the silica gel and adsorbed oil comv ponents with said vparaiini hydrocarbon whereby paraiinic and, naphthenic constituents of high viscosity index are desorbedfrom the silica gel., lfractio'nating high viscosity index constituents from the wash paraflinic hydrocarbon by distillation removing the said paraiinic hydrocarbon as an overhead product, and thereafter recycling said overhead product to the said silica gel contacting the silica gel in liquid phase at about the boiling point of the parainic hydrocarbon,v

whereby the said silica gel is regenerated.

2. The processdened by claim 1 in whichthe' said parafnic hydrocarbons isn-heptane.

3. In a silica gel lubricating oil treating process in which the lubricating, oil lis diluted with a parainic hydrocarbon containing from 3 to 10 carbon atoms and boiling in the range of about 100to 300 F., the steps which comprise contacting silica gel with the said Adiluted lubricating oil, whereby/substantially all of vsaid oil is adsorbed by the silica gel, Washing said .silica gel with said parailinic hydrocarbon at about ambient temperatures whereby paranic and .gaphthenic constituents of highviscosity index are desorbed from the silica gel, withdrawing said wash paraf-` nic hydrocarbon and said desorbed constituents and segregating the highV viscosity index constituents from the paraiilnic hydrocarbon by distillation providing a vaporous overhead. stream of paranic hydrocarbon, subsequently condensing said.overhead paraiinic hydrocarbon and contacting the said treated silica gel with the condensed paraffinic hydrocarbon whereby low viscosity index constituents aredesorbed from the silica gel, and nally contacting the saidtreated silica gel with vapors of the said parainic hydrocarbon to secure the condensation of the said vapors and the contact of thesilica gel with theV paralnic hydrocarbon in liquid .phase at about the boiling point of the parainic hydrocarbon.

4. The process defined by claim 3 in which the said parafnic hydrocarbon is n-heptane. INSLEY P. JONES.

REFERENCES CITED The .following references are of record in the le of this patent:

UNITED STATES PATENTS 2,470,339 Claussen et al. May 17, 1949 

1. A SILICA GEL LUBRICATING OIL TREATING PROCESS IN WHICH LUBRICATING OIL DILUTED WITH A PARAFFINIC HYDROCARBON CONTAINING FROM ABOUT 3 TO 10 CARBON ATOMS AND BOILING IN THE RANGE OF ABOUT 100 TO 300* F. IS SUBSTANTIALLY ADSORBED ON SILICA GEL BY CONTACT THEREWITH, SUBSEQUENT TO SAID CONTACTING WASHING THE SILICA GEL AND ADSORBED OIL COMPONENTS WITH SAID PARAFFINIC HYDROCARBON WHEREBY PARAFFINIC AND NAPHTHENIC CONSTITUENTS OF HIGH VISCOSITY INDEX ARE DESORBED FROM THE SILICA GEL, FRACTIONATING HIGH VISCOSITY INDEX CONSTITUENTS FROM THE WASH PARAFFINIC HYDROCARBON BY DISTILLATION REMOVING THE SAID PARAFFINIC HYDROCARBON AS AN OVERHEAD PRODUCT, AND THEREAFTER RECYCLING 